Crash risk is highly elevated among novice teenage drivers, particularly during the first year of independent driving. The elevated risk of this period appears to be caused by some combination of inexperience and risk taking. Crash risks are greater at night than day for all drivers, but this is particularly true for young drivers. Passengers create no increase in risk among older drivers, but each additional passenger significantly increases the risk for a fatal crash among young drivers. Crashes among young drivers, compared with crashes among older drivers, are more likely to involve speeding and driver error. It is unclear the extent to which the high crash risks among young drivers are due to lack of experience, driving conditions, risk taking, or a combination of these factors. In a previous naturalistic study, the vehicles of 100 high-mileage drivers age18 and older were instrumented with cameras, motion sensors, and the like to determine the factors associated with crashes and near crashes. The current study will examine crash risks among 40-newly licensed 16 and 17 year olds and will evaluate the effect of experience on driving performance, particularly in the presence and absence of teen passengers and at night compared with day, during the first 18 months of licensure. We have recruited 40 novice teen drivers within a few weeks of licensure and instrumented their vehicles with cameras and other equipment to assess driving performance and factors associated with crashes and near crashes. Two of the teens share a vehicle with parents, who are also part of the study. For 18 months, data from all of the participants[unreadable] driving is collected, stored electronically on a hard drive in the trunk of the vehicle, and downloaded monthly. The study outcomes include the factors inside and outside the vehicle associated with crashes and near crashes and changes in driving performance over time, at night vs day, and with and without teen passengers. Both teen and parent study participants also complete assessments of driving performance on a test track at baseline and 12 months.